Coherent construction of recovered γ-Al2O3 embedded N-doped activated carbon by supercritical-CO2 pathway: Robust hybrid electrode material for energy storage device

Electrochemical energy storage application is one of the most impressive solutions to the problem of fossil fuel depletion. However, the lower capacitance in electric double-layer capacitors and poor stability in pseudocapacitors remain significant challenges. State of an art, we demonstrated the fabrication of hybrid electrode material with aluminium oxide nanoparticles (Al2O3 NPs) embedded in N-doped activated carbon (AC) by supercritical-CO2 approach. The N-doped activated carbon and Al2O3 NPs were prepared by Dracaena trifasciata biomass and the strategic recovery of domestic aluminium waste. The prepared materials were inspected through microscopic and various spectroscopic techniques. The morphological observation of Al2O3@DT-AC manifested well impregnation of Al2O3 NPs to DT-AC surface, resulting in a higher capacitance of 1031.6 F/g at 0.5 A/g than Al2O3 (258.5 F/g). Further, the respectable capacitance retention signifies that Al2O3@DT-AC are promising electrode materials for supercapacitors. The material preparation and processing techniques are eco-friendly and considered to be green processing. •Al2O3NPs@DT-AC was fabricated via a supercritical-CO2 process.•Al2O3 NPs were recovered from domestic aluminium waste.•N-doped activated carbon was prepared from Dracaena trifasciata biomass.•The fabricated Al2O3NPs@DT-AC electrode showed good Csp (1031.6 F/g at 0.5 A/g).•Al2O3NPs@DT-AC exhibited splendid Csp retention of 93.18 % even after 5000 cycles.